1. Field of the Invention
This invention relates generally to devices and methods used in the treatment of equine lameness, and more particularly to those devices and methods directed to shifting at least some of the weight of the animal to the frog portion of the foot.
2. Description of the Related Art
Horse owners, farriers and large animal veterinarians are familiar with lameness in horses. The most common causes of lameness are laminitis, underrun heels, quarter cracks and related conditions such as road founder. Equine laminitis is a disorder of the pedal laminae that form the supportive bond between the hoof and third phalanx. Treatment of lameness in horses typically involves some form of special shoeing and/or treatment of the feet of the horse to alleviate pain, shift weight away from painful areas of the foot, support the foot to halt deterioration and promote healing.
Since foot support appears to satisfy a number of treatment goals, namely partial alleviation of pain, the slowing of further movement of the phalanx (in laminitis), and healing of cracked hooves, a number of interesting remedial devices and methods have been created. For example, one of the more common devices is known as the xe2x80x9cheart bar shoexe2x80x9d. This device looks similar to a conventional horseshoe except for the addition of a V-shaped extension that supports the frog. Depending on the specific anatomical features of the affected foot, the nature and extent of the problem, the apex of the V-shaped extension can be raised or lowered to provide more or less frog support. Another device used for frog support is known as the xe2x80x9clily padxe2x80x9d, which fits on to the heel of the affected foot but which also includes a V-shaped extension. Finally, others have suggested the use of soft pliable material to provide resilient support for the frog.
Unfortunately, because much effort has been directed toward custom-fit support systems, the complexity of such systems has increased with variable success in the alleviation of pain from one animal to another. Heart bar shoes, for example, can be applied only after careful scrutiny of the geometry of the affected foot and most often require the services of an expert farrier. In fact, improper preparation or use of these methods can actually aggravate the laminitis condition and cause greater pain for the affected animal.
The frog is a generally triangular elastic horny pad, that is situated in the space between the quarters and bars of a horse hoof. This position places the frog beneath the bony column of the equine leg, making it a convenient place to shift weight. The sole of the equine foot is slightly concave with the centrally located frog elevated relative to the horny perimeter wall of the hoof. This relative positioning requires a weight shifting apparatus to project upwardly from the horseshoe which is typically fastened to the wall of the hoof.
A horse experiencing extreme foot pain may be unable to move and/or exercise. Lack of movement seriously impedes blood flow to the horse""s feet. Blood is necessary for normal growth, functioning and repair of injured tissues. Blood is pumped by the equine heart through arteries to the foot and is assisted in its return to the heart by a xe2x80x9cpumping mechanismxe2x80x9d in the foot. This mechanism must be present due to the position of the foot in relation to the heart.
There are no muscles in the lower leg or foot, as we find in other parts of the body, to aid in the returning venous blood to the heart. Located on both sides of each of the lateral cartilages and in the sensitive structures of the foot are large venous plexuses. Each venous plexus is made up of an extensive network of veins. The compression of these veins by the frog against the lateral cartilages acts as a pump to force the blood up the leg and back to the heart. Blood is prevented from returning to the foot by valves in the veins of the leg. This valve action creates a fluid pressure which causes the blood to exit up the leg and the plexuses to fill when the foot is raised and compressed veins open. Each time the foot bears weight, the veins are compressed. Each time the foot is raised, the veins open and blood is pushed in by the arterial pulse and gravity.
Treatment that is effective at alleviating pain permits the horse to move more normally, improving blood flow in and around the feet to aid healing. Some treatments, such as heart bar shoes, may impede the pumping action of the hoof by rigidly supporting the frog with respect to a horseshoe rigidly fixed to the peripheral wall of the hoof. Inadequate blood flow impedes healing and can lead to necrosis in the foot.
An object of the present invention is to provide a new and improved equine support pad with integral frog support that does not require the services of an expert farrier for installation.
Another object of the present invention is to provide an equine support pad and frog support that does not impede normal blood pumping through the equine foot.
A further object of the invention is to provide a new and improved equine support pad with integral frog support that alleviates foot pain by shifting weight from the hoof wall to the frog.
A yet further object of the present invention is to provide a new and improved equine support pad with integral frog support that permits access to the sole of the foot between the hoof wall and the frog.
One preferred embodiment of an equine support pad with integral frog support in accordance with the present invention comprises a wedge pad of substantially non-compressible polymer material configured for attachment between a horse hoof and a horseshoe. The pad is configured in an oval shape to generally conform to the configuration of the equine hoof. The central portion of the support pad is generally open, allowing access to the sole of the foot between the hoof wall and the frog. A frog support projects into the central opening of the pad in a generally triangular configuration that mimics the anatomy of the frog. The point of the triangular frog support is located in the middle of the opening in the pad and is generally free to move independently of the pad.
The frog support widens as it projects toward the heel end of the pad to provide a continuous substantially planar frog support surface. This triangular frog support surface is configured to project above the foot side of the pad such that the point of the triangular frog support is elevated relative to the hoof side of the pad. Conversely, the opposed ground contact face of the frog support is configured to project to the same level as the traction (bottom) surface of a horseshoe mounted to the shoe side of the pad. The flexible material of the support pad permits the frog support to flex relative to the peripheral portions of the support pad which will typically be rigidly secured to the wall of the hoof by the horseshoe and nails.
When the animal places weight on a hoof equipped with the inventive pad, the ground contact face of the frog support diverts weight away from the hoof wall to the bony column of the leg by contacting the frog. The flexible material of the pad/frog support and the open configuration around the tip of the frog support permit the frog support to flex upwardly (when delivering weight to the frog) and back (when the leg is unweighted). This movement permits and even improves blood flow in the natural pump in the equine foot.
The shoe side of the pad is configured to accommodate egg bar, straight bar and open shoes. The ground contact face of the frog support does not extend all the way to the heel end of the pad, creating an uninterrupted shoe-mounting surface around the entire periphery of the support pad opposite the hoof surface.